1988 Honda Civic wagon 4WD 5 speed ~140K
Car runs and drives fine, except that every now and then (every few weeks or so), the engine idle will start to surge and fall, surge and fall when I’m sitting at a stop light. It reves up to about 500, then drops down to just under a 1000(give or take, but it isn’t more than about 700 rpm difference overall). This has always
cleared up by the next day, and has never been an issue when the car is moving -
no surges, tach fluttering, etc.
The other week though, while I was driving along, the tach started shooting up and down, and the engine died. I pulled over, and it wouldn’t restart. I tried it again 5 minutes later and it started right up, with absolutely no indication there was any problem. Fluids looked fine, temp gauge was ok, etc. Car ran and drove
with no issues…
Fast forward to this morning, and the car did the same driving along and dying thing. The only difference is now the engine is surging/falling at idle now and it hasn’t gone away.
I can only assume the problems are related somehow, but I have no idea where to start looking. I had a tune up a few weeks ago, so I know (at least I assume) that I have good plugs, wires, and fuel filter. I do feel like my fuel economy has dropped recently though, from around 30-31 mpg around town to about 26-27. I live in Virginia and it hasn’t been especially cold.
Can someone take a guess here and tell me what they think? I’d love to keep this car going - it’s been very reliable for me.
Thanks!
Josh
Any ideas guys?
While the plugs and all may be good, something may have come loose. I would check the cables to make sure they are tight, and also make sure that everything else is tight. Then look for a code from the computer, that would be a help in starting where to look. Things to look for might be the oxygen sensor, the mass air flow sensor, if so equipped, or the idle or throttle sensor.
Any of those could be the cause.
Try bleeding your coolant and make sure it is a 50/50 mix. Air bubbles in the coolant are bad. Look for a vacuum leak anywhere, this can cause a surging idle. Your IACV may also be the culprit.
This problem has nothing to do with spark plugs or oxygen sensors. It is a problem with your engine not knowing whether it is warmed up or not.
What would cause the “confusion” of the car not knowing it was warm or not? Is it a specific part that can be checked/replaced?
Like I said, bubbles in the coolant or a malfunctioning IACV are two likely candidates.
Oh…IACV = Idle Air Control Valve by the way.
Is this car fuel injected or carburated? I don’t know Civs from that time, but I know that Accords were made both ways ca. 1988.
Is this car the Wagovan? Open the hood and look at the engine. On the top of the engine, do you see PGM-FI or, maybe TBI?
In the event the iac valve (idle air control) might be sticking, pull the large black plastic intake tube and spray the throttle plate and “stuff” with a generous spraying of carb/throttle body cleaner. Let sit a few minuets, and start and idle. Expect a smoky exhaust.
It is fuel injected.
It is the Wagovan…I’ll give your suggestion a try tomorrow, thanks!
Both TBI and PGM-FI are forms of fuel injection. The TBI looks like a carburetor. It has one fuel injector. The PGM-FI has 4 fuel injecters…one at each cylinder. Using the carb/throttle body spray (or, liquid) cleaner applies to both types.
Just wanted to update - I had a friend clean the throttlebody and the Idle Air Control Valve with carb/throttle cleaner and that fixed the idle right up.
THANKS GUYS!!